Method for precisely measuring position of a part to be inspected at a part inspection station

Abstract

A method for precisely measuring position of a part to be inspected at a part inspection station is provided. The method includes positioning a part having a part axis relative to a measurement axis at the part inspection station and scanning the positioned part with an array of planes of radiation so that the part occludes each of the planes of radiation over a measurement interval of the part to create a corresponding array of unobstructed planar portions of the planes of radiation. Each of the unobstructed planar portions contains an amount of radiation which is representative of a respective geometric dimension of the part. The method also includes measuring the amount of radiation present in each of the unobstructed planar portions to obtain measurement signals and processing the measurement signals to obtain a geometric measurement between the axes at the measurement interval. The geometric measurement may be a distance between the axes or angle between the axes. If the geometric measurement is outside an acceptable range of geometric values, the method may further include repositioning the part until the geometric measurement between the axes at the measurement interval is within the acceptable range of geometric values.

1. A method for precisely measuring position of a part to be inspected at a part inspection station, the method comprising:
 positioning and supporting a part having a width and a part axis relative to a measurement axis at the part inspection station; 
 scanning the positioned and supported part with an array of planes of radiation, each of the planes having a width greater than the width of the part so that the part occludes each of the planes of radiation over a measurement interval of the part to create a corresponding array of unobstructed left and right planar portions of the planes of radiation which pass by and are not blocked by the supported part wherein each of the unobstructed planar portions contains an amount of radiation which is representative of a respective geometric dimension of the part; 
 measuring the amount of radiation present in each of the unobstructed planar portions to obtain measurement signals; 
 processing the measurement signals to obtain a geometric measurement between the axes at the measurement interval; and 
 storing the geometric measurement. 
 
   
   
     2. The method as claimed in  claim 1 , further comprising, if the geometric measurement is outside an acceptable range of geometric values, repositioning the part until the geometric measurement between the axes at the measurement interval is within the acceptable range of geometric values. 
   
   
     3. The method as claimed in  claim 2 , wherein the geometric measurement is a measure of distance between the axes and wherein the step of repositioning includes centering the part at the station. 
   
   
     4. The method as claimed in  claim 2 , wherein the geometric measurement is a measure of angle between the axes and wherein the step of repositioning includes aligning the part with respect to the measurement axis at the station. 
   
   
     5. The method as claimed in  claim 1  further comprising comparing the geometric measurement with a predetermined acceptable geometric value. 
   
   
     6. The method as claimed in  claim 1 , wherein the measurement interval is user-selectable and wherein the method further comprises receiving a signal which indicates the user-selectable measurement interval of the part. 
   
   
     7. The method as claimed in  claim 1  further comprising generating a signal if the geometric measurement is outside the acceptable range of geometric values. 
   
   
     8. The method as claimed in  claim 1 , wherein the step of scanning includes the step of linearly moving the array of planes of radiation relative to the part. 
   
   
     9. The method as claimed in  claim 1 , wherein the number of planar portions is twice the number of the planes of radiation. 
   
   
     10. The method as claimed in  claim 1 , wherein each of the planes of radiation scans the part from a different azimuthal direction relative to the measurement axis. 
   
   
     11. The method as claimed in  claim 10 , wherein the planes of radiation have a substantially uniform azimuthal spacing relative to the measurement axis. 
   
   
     12. The method as claimed in  claim 1 , wherein none of the planes of radiation are coplanar. 
   
   
     13. The method as claimed in  claim 1 , wherein the planes of radiation are spaced apart. 
   
   
     14. The method as claimed in  claim 1 , wherein the radiation is laser radiation. 
   
   
     15. The method as claimed in  claim 14 , wherein the laser radiation is visible. 
   
   
     16. The method as claimed in  claim 1 , wherein adjacent pairs of unobstructed planar portions created from the same planes of radiation are coplanar. 
   
   
     17. The method as claimed in  claim 1 , wherein the step of processing includes the step of processing the measurement signals to obtain coordinates of a midpoint of the measurement interval. 
   
   
     18. The method as claimed in  claim 17 , wherein the step of processing includes the step of calculating distance between the axes based on the coordinates of the midpoint. 
   
   
     19. The method as claimed in  claim 1 , wherein the step of processing includes the step of processing the measurement signals to obtain coordinates of a midpoint of each of a pair of spaced slices of the measurement interval. 
   
   
     20. The method as claimed in  claim 19 , wherein the step of processing includes the step of calculating angle between the axes based on the coordinates of the midpoints. 
   
   
     21. A method for precisely measuring position of a part to be inspected at a part inspection station, the method comprising:
 positioning and supporting a part having a width and a part axis relative to a measurement axis at the part inspection station; 
 scanning the positioned and supported part with an array of planes of radiation, each of the planes having a width greater than the width of the part so that the part occludes each of the planes of radiation over a measurement interval of the part to create a corresponding array of unobstructed left and right planar portions of the planes of radiation which pass by and are not blocked by the supported part wherein each of the unobstructed planar portions contains an amount of radiation which is representative of a respective geometric dimension of the part; 
 measuring the amount of radiation present in each of the unobstructed planar portions to obtain measurement signals; 
 processing the measurement signals to obtain a measure of distance between the axes at the measurement interval; and 
 storing the measure of distance. 
 
   
   
     22. A method for precisely measuring position of a part to be inspected at a part inspection station, the method comprising:
 positioning and supporting a part having a part axis and a width relative to a measurement axis at the part inspection station; 
 scanning the positioned and supported part with an array of planes of radiation, each of the planes having a width greater that the width of the part so that the part occludes each of the planes of radiation over a measurement interval of the part to create a corresponding array of unobstructed left and right planar portions of the planes of radiation which pass by and are not blocked by the supported part wherein each of the unobstructed planar portions contains an amount of radiation which is representative of a respective geometric dimension of the part; 
 measuring the amount of radiation present in each of the unobstructed planar portions to obtain measurement signals; 
 processing the measurement signals to obtain a measure of angle between the axes at the measurement interval; and 
 storing the measure of angle.